Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Rapid warming caused vegetation changes

14.11.2005


Fossil leaves buried 55 million years ago show, for the first time, that rapid warming not only changed animal communities, but plant communities as well; and that the ancient warm spell may be representative of global warming’s effects in Earth’s future, according to an international team of researchers.



"There has been an absence of fossil leaf sites dating to the Paleocene-Eocene Thermal Maximum (PETM)," says Dr. Francesca A. Smith, postdoctoral researcher in geosciences, Penn State.

Scientists have long known that during the PETM, mammalian communities changed, but without plant fossil samples, they could not say the same for plants. The PETM is unusual because the warming of 9 to 18 degrees Fahrenheit occurred in only 10,000 years, a geologically short time span. Researchers believe that increased carbon dioxide caused the warming, but underlying causes of the increase are still being debated. "The PETM provides an important analog to present-day anthropogenic global warming, because the two episodes are inferred to have similar rates and magnitudes of carbon release and climate change," the researchers report in today’s (Nov. 11) issue of Science.


Dr. Scott Wing, Department of Paleobiology, Smithsonian Museum of Natural History, led the expedition to the southeastern Bighorn Basin, Wyoming, that found new boundary sequences of fossils that covered the change from the Paleocene to the Eocene. These sequences, unlike those found in the past, contained both leaf and pollen fossils.

"Finding fossil leaves from this period is difficult," says Smith. "Leaves are only rarely preserved and the fossil beds for this time period are only 130 to 160 feet thick."

To ensure that the new areas were actually in the proper time period, the researchers used two dating methods. Smith and Dr. Katherine H. Freeman, professor of geosciences, Penn State, looked at the chemical signature of the carbon in the fossils. From marine sediment studies, researchers know that during this time period, the heavier form of carbon, carbon 13, occurred less frequently in the atmosphere. Smith and Freeman identified these fossil beds as having the proper carbon composition for the PETM. Coupling carbon with the mammalian fossils found in the beds, including the oldest known horses that were the size of a cat and the ancestors of modern primates, the researchers identified the beds as coming from the PETM.

Analysis of the plant fossils showed that the plants from before and after the PETM were from typical forests for the time, containing relatives of dawn redwood, alder, sycamore, walnut and sassafras. However, the bean family, including relatives of poinsettia, sumac and paw-paw, dominate the fossils during the PETM. These are plants more commonly found during that time period, 1,000 miles to the south in Mississippi, Louisiana and Texas. These plants migrated north in 10,000 years or less.

The leaf fossils also allowed researchers to look at the PETM climate. By comparing the numbers of smooth edged leaves to toothed leaves, they found that the temperature change in the Bighorn basin was about 9 degrees Fahrenheit warmer during the PETM. By looking at the leaves’ surface areas, researchers could estimate precipitation.

"Using these methods, we can infer the temperature changes and determine that the area was dry at the beginning of this period and wet toward the end," says Smith. "Rainfall declined about 40 percent and later recovered."

At the end of the PETM, forests returned to their original composition with the addition of plants like relatives of the wingnut and linden that migrated into the area from Europe across Arctic land bridges. "So much of the information that we have about ancient terrestrial climate during the PETM comes from the Bighorn basin area because it is one of a handful of terrestrial sequences for that time period," says Smith "To interpret the record, we need to have as much information as we can get."

According to Wing, similarly rapid changes in flora might be expected in the future as a result of human-induced global warming.

A’ndrea Elyse Messer | EurekAlert!
Further information:
http://www.psu.edu

More articles from Ecology, The Environment and Conservation:

nachricht Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen

nachricht A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>